Dry seal gas holder



Aug. 12, 1952 J. w. ALLEN DRY sEAL- GAS HOLDER Filed Feb. 16, 1949 FIG.|.

FIG.2.

ooo oo o I NVENTUR JOHN. W. ALLEN MKM A TTORNE Y Patented ug. 12, 14952 per SEAL GAS Homan v `ioliurifw. Allen, Chicago, Ill., assigner to John H. Wiggins, Chicago, Ill.

Applicaties February 1c, 1949,seria1 No. A'76,790

(ci. lis-178) 6y Claims. l

Y This invention relates to gas holdersand other iiuid storage apparatus of the kind'that comprise a container, a vertically-movable piston in said container, a sealing means for said piston comprising a plurality of flexible, fabric sealing elements, one of which is attached to the container ,side wall and one of which is attached to the peripheral portion of the pistonand a pressureabsorbing structure for said piston sealing means, comprising an annular back sto-p member rigidly mounted on and projecting upwardly from; the top side of the piston,` and a {3o-operating, vertically-movable, annular back stopV member attached to said eXib-le piston sealing elements and adapted to move vertically relatively'to the piston and relatively to the container side wall during the cycle of operations ci the piston, as disclosed in my pending application Serial No, 752,434, iiled June 4, 1947, now U. S, Pat. No. 2,554,767 dated May 29, 1951.

One object of my present invention is to construct the vertically-movable back-stop of an apparatus of the general kind above referred to, in suoli a manner that the fab-ric, piston sealing element adjacent the piston will not wrinkle excessively at the point where it is attached tothe piston, or when said element is backed up by the vertically-movable back-stop member between the piston andthe container side wall, even though the piston and the container side wall are in widely spaced relationship.

Another object is to reduce the quantity of gastight fabric used in the piston sealing means, thus effecting a saving in the cost ci constructing said means and also reducing the area of the portion of said means in which gas leaks are liable to develop. c

Another object is to provide an apparatus of the kind above referred to, in which the container is constructed in a novel manner so as to provide a support for the vertically-movable back-stop when the piston is at the end of its downward stroke.

And-still another object of my invention is to construct the container of an apparatus of the kind mentioned in a novel manner that greatly reduces the dead space of the gas storage chamber, when said chamber is empty.

Figure 1 of the drawings is a fragmentary, vertical, transverse-sectional view of a gas holder embodying my present invention; and

Figure 2 is a fragmentary, vertical, transversesectional View, illustrating another form of my invention. k

In the accompanying drawings, A designates the roof of the container of the apparatus, B and C designate the side wall and bottom, respectively, of the container, and D designates the piston which reciprocates vertically inthe container,

due to variation in pressure of the gases confined.

in the storage chamber, said storage chamber being formed by the piston, by the bottom ofthe container, by the lower end portion of the con'- tainerside Wall, and by a piston'sealing means attached tothe container side wall and to the periphery of the piston, and constructed Yin such' a manner as to provide for the vertical movement of the piston. My presentinventicn, briefly stated, consists in constructing theY above-mentioned piston sealing means from two gas-tight fabric elements of diiierent circumference, arranged in widely spaced relationship between the piston and the container side wall, and avertically-movable back-stopV structure interposed between and attached vto said fabric elements andl provided with a substantiallyhorizontally-disposed annular member that occupies or takes up a considerable portion of the transverse width of the space between the piston and the container side wall, said back-stop structure also comprising a pair of concentricmertical, cylindrical backing members projecting upwardly Y from said annular horizontal 'member and adapted to back up and reinforce said fabric sealing elements during the cycle of operations of the apparatus.`

In the preferred form of my `invention herein shown, the Vpiston sealing means is composed of twoflexible, annular-shape sealing elements i and 2, of different circumference, constructed of gas-tight fabric, and a substantially flat, horizontally-disposed, annular metal member 3, arranged between said fabric elements i and 2 and connected to same in a gas-tight manner, said intermediate metal member 3 taking -up a portion of 'the transverse width or" the space between the piston and the container `side wall. In large gas holders the intermediate member ,3A to which the fabric elements I and 2 are attached.,y is relatively wide and `may have a Width of tvv'o feet or more. As shown in the drawings, the outer sealing element I is attached to an intermediate portion of the container sidewall B, and the inner sealing element 2 is. attached to,` the peripheral portion of the piston D,v thus producing a gas-tight closure for the space between the, piston and container side wall, composed of vtwo, fabric elements of different circumference, arranged in widely-spaced relationship and attachedrespectively, to the stationary and movable parts of the apparatus, and an intermediate metal member attached to said fabric elements and bridging the gap between the same. The above mentioned intermediate member 3 of the piston sealing structure forms part of a vertically-movable back-stop structure, designated as an entirety by the reference character E, which is equipped with two separate and distinct concentric, vertical, cylindrical abutment members E' and E2 that back up and reinforce the fabric sealing elements l and 2, respectively, as hereinafter described. Preferably, the abutment members E' and E2 are combined with the annular member 3 in such a way as to produce an annular back-stop E of channel shape in cross section, whose horizontal web constitutes a substantially iiat, horizontally-disposed surface 3, that is presented to the medium conned in the storage chamber, and whose vertical legs constitute two concentrically-disposed, cylindrical, vertical abutment members for the fabric sealing elements l and 2 attached to the piston andto the container side wall. n

As is usual in piston type, dry seal gas holders of the general kind previously mentioned, the piston D is provided on its top side with a cylindrical abutment member F that acts as a backstop for the inner fabric sealing element 2, when the piston is at the end of its downward stroke. Any suitable means may be used to cause the vertically-movable back-stop E toY rise and fall with the piston during the cycle of operations of the piston, such, for example, as an annular girder member or compression member at the upper end of the back-stop E, disposed so that during the upward travel of the piston from its lowermost position, shown in full lines in Figure l, the abutment member F on the piston will engage said girder member 4, and thus impart upward movement to the back-stop E, as indicated in broken lines in Figure 2. In my improved gas holder, when the back-stop E is not moving with the piston or sustained by the piston, said back-stop remains at rest at the lower end of the container, with the bottom piece 3 of said back-stop disposed in a higher horizontal plane than the bottom C of the container. Various means may be used to support the back-stop E when it occupies this position. In the form of my invention shown inFigure l, the side wall of the gas storage chamber is provided with a plurality of laterally-projecting brackets 5 that form a horizontal supporting surface on which the back-stop VE rests squarely and rmly when said back-stop is at rest. In the form of my invention shown in Figure 2, the side wall of the contaner of the apparatus is offset inwardly at its lower end for the dual purpose of reducing the volume of the dead space of the gas storage chamber when said chamber is empty, and for forming a horizontally-disposed ledge '.52L that will support the back-stop E in a position higher than the bottom C of the gas storage chamber When said back-stop is in a quiescent state. an inwardly-off-set in the side wall reduces the dead space to approximately 0.2% of the gas holder capacity, with the result that purging of the storage chamber, when it is empty, as indicated in broken lines in Figure 2, will not normally be necessary.

When the piston D is at the end of its downward stroke, the gases in the storage chamber force the fabric sealing element l into snug engagement with the abutment member E on the back-stop E, and force the fabric sealing element 2 into snug engagement with the abutment mem- SuchV ment with the abutment member E2.

4 ber F on the piston. The back-stop E remains' at rest during the first portion of the upward stroke of the piston, and the upward movement of the piston, in conjunction with the pressure exerted by the gases on the sealing element. 2, causes said sealing element to be progressively stripped off the piston abutment member F and progressively applied to the abutment member E2 on the back-stop E. When the piston reaches such a height that the abutment member F on the piston engages the overhanging beam member or compression member 4 on the back-stop E, said back-stop will start to move upwardly with the piston, at the same speed as the piston, with the result that the sealing element I will be progressively stripped oil the abutment member .E on the back-stop E and progressively applied to the upper end portion of the side wall of the container, as shown in broken lines. During the downward stroke of the piston, the back-stop E moves downwardly at the same speed as the piston, thus causing the sealing element l to be progressively stripped off the upper portion of the container side wall and progressively applied to the abutment member E on the back-stop E, after which said back-stop comes to rest on the horizontal supporting surface 5 and 5B near the bottom of the gas storage chamber. During this portion of the cycle of operations, i. e., when the sealing element l is being re-engaged with the abutment member E on the back-stop E, the sealing element 2 remains in engagement with the abutment member E2 on the back-stop E., but after the back-stop E has come to rest, the continued downward movement of the piston causes the sealing element 2 to be progressively stripped ofi the abutment member E2 on the backstop, and progressively applied to the abutment member F on the piston.

One of the main advantages of the apparatus herein described is that the inner sealing element 2 will not pucker excessively at its inner edge, where it is attached to the piston, and said element will be free of wrinkles when it is in engage- I attain this highly desirable result by using the bottom part 3 of the vertically-movable back-stop E to form the intermediate portion of the seal between the pistonr and the container side wall, using a tubular-shaped fabric element 2 of substantially the same circumference as said bottom part 3, to form the portion of said seal that is adjacent to and attached to the piston, and using a tubular-shaped fabric element l of greater circumference than the element 2 to form the portion of said seal that is adjacent to and attached to the container side wall. The transverse width of the bottom part 3 of the vertically-movable back-stop will vary according to the sizeof thev apparatus. VIt may be six inches, or less, in a small gas holder, and it may be two feet, or more,

in a large gas holder. However, the inner vsealing element 2 attached to the piston will always be of less circumference than the outer sealing ele-v l ment, attached to thecontainer side wall, and moreover, will have a circumference substantiallyY the same as the abutment member E2 to which the inner edge of said outer sealing element 2 is attached. This permits the inner edge of the inner sealing element 2 to be attached to the, piston without creating wrinkles, puckers or folds of excessive size in said element, due, of course, to the fact that the circumference of the abutment member E2 is not greatly in excess ofthe circumference of the piston. If the seal between the piston and the container side wall were formed by a single, tubular-shaped fabric element of the same circumference as the container side wall, the circumference of the inner edge of said element would have to be reduced to such a degree or extent, in order to make it fit the piston, that wrinkles, puckers, or folds of excessive size would form in said fabric element, due to the excess material in the portion of said fabric element Iadjacent to and attached to the piston. In my improved piston sealing means the inner portion of the seal adjacent the piston contains considerably less material than the outer portion of the seal adjacent the container side wall, it is of considerably less circumference than the said outer portion of the seal, and the difference in circumference between the outer and inner edges of the Iportion of the seal attached to the piston is not so great as to produce excessively large wrinkles or folds in same. My invention also effects a considerable saving in the cost of the fabric sealing elements, due to the reduced quantity of material required to construct the same. My invention minimizes the possibility of leaks in the piston sealing means, due to the reduction in the area of the fabric portion of said sealing means. Still another advantage is that said back-stop, when it is at rest, is disposed at a level considerably higher than the bottom of the ygas storage chamber, thus permitting the dead space of said chamber to be diminished, as previously explained, and also making it possible to use an inexpensive supporting structure for the vertically-movable backstop on which said back-stop rests firmly and squarely, when said back-stop is not sustained by the piston.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid storage apparatus, comprising a container having a side wall, a vertically movable piston in said container spaced away from the side wall of same, a vertically movable back-stop structure arranged in the space between the piston and the container side-wall and comprising an annular horizontal member and a pair of concentric, vertical, cylindrical backing members projecting upwardly from said annular horizontal member, and two fabric sealing elements, the rst sealing element being attached at its outer edge to the container side Wall and at its inner edge to the back-stop structure adjacent said annular horizontal member and the second sealing element being attached at its inner edge to the piston and at its outer edge to the backstop structure adjacent said annular horizontal member.

2. An apparatus of the kind described in Iclaim 1, provided with means for causing the backstop structure to move vertically with the piston during portions of the stroke of the piston.

3. An apparatus of the kind described in claim 1, in which the piston has attached to same, a vertical cylindrical, upwardly projecting backing member arranged in concentric relation with the pair of backing members on said back-stop structure.

4. An apparatus of the kind described in claim 1, in which the pair of backing members on the back-stop structure are arranged outside of the storage lchamber of the apparatus and form no portion of the confining wall of said storage chamber.

5. An apparatus of the kind described in claim 1, which also includes stop means to limit the downward travel of the piston.

6. An apparatus of the kind described in claim l, in which the side wall of the storage chamber of the apparatus is provided at its lower end with an inwardly off-set portion that reduces the dead space of the storage chamber and also serves as a support for the back-stop structure when said back-stop structure is in its lowermost position.

JOHN W. ALLEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A FLUID STORAGE APPARATUS, COMPRISING A CONTAINER HAVING A SIDE WALL, A VERTICALLY MOVABLE PISTON IN SAID CONTAINER SPACED AWAY FROM THE SIDE WALL OF SAME, A VERTICALLY MOVABLE BACK-STOP STRUCTURE ARRANGED IN THE SPACE BETWEEN THE PISTON AND THE CONTAINER SIDE-WALL AND COMPRISING AN ANNULAR HORIZONTAL MEMBER AND A PAIR OF CONCENTRIC, VETTICAL, CYLINDRICAL BACKING MEMBERS PROJECTING UPWARDLY FROM SAID ANNULAR HORIZONTAL MEMBER, AND TWO FABRIC SEALING ELEMENTS, THE FIRST SEALING ELEMENT BEING ATTACHED AT ITS OUTER EDGE TO THE CONTAINER SIDE WALL AND AT ITS INNER EDGE TO THE BACK-STOP STRUCTURE ADJACENT SAID ANNULAR HORIZONTAL MEMBER AND THE SECOND SEALING ELEMENT BEING ATTACHED AT ITS INNER EDGE TO THE PISTON AND AT ITS OUTER EDGE TO THE BACKSTOP STRUCTURE ADJACENT SAID ANNULAR HORIZONTAL MEMBER. 